Log type that has failed to deserialize itself from a request

src/github/api.rs

@@ -1,3 +1,4 @@
+use crate::utils::ResponseExt;
 use anyhow::{bail, Context};
 use hyper_old_types::header::{Link, RelationType};
 use log::{debug, trace};
@@ -138,7 +139,7 @@ impl GitHub {
             };
             Ok(self
                 .send(Method::POST, &format!("orgs/{org}/teams"), body)?
-                .json()?)
+                .json_annotated()?)
         }
     }
 
@@ -366,7 +367,7 @@ impl GitHub {
         } else {
             Ok(self
                 .send(Method::POST, &format!("orgs/{org}/repos"), req)?
-                .json()?)
+                .json_annotated()?)
         }
     }
 
@@ -761,7 +762,7 @@ impl GitHub {
     ) -> Result<Option<T>, anyhow::Error> {
         let resp = self.req(method.clone(), url)?.send()?;
         match resp.status() {
-            StatusCode::OK => Ok(Some(resp.json().with_context(|| {
+            StatusCode::OK => Ok(Some(resp.json_annotated().with_context(|| {
                 format!("Failed to decode response body on {method} request to '{url}'")
             })?)),
             StatusCode::NOT_FOUND => Ok(None),
@@ -785,7 +786,7 @@ impl GitHub {
             .send()?
             .custom_error_for_status()?;
 
-        let res: GraphResult<R> = resp.json().with_context(|| {
+        let res: GraphResult<R> = resp.json_annotated().with_context(|| {
             format!("Failed to decode response body on graphql request with query '{query}'")
         })?;
         if let Some(error) = res.errors.get(0) {
@@ -1059,19 +1060,3 @@ pub(crate) enum BranchProtectionOp {
     CreateForRepo(String),
     UpdateBranchProtection(String),
 }
-
-trait ResponseExt {
-    fn custom_error_for_status(self) -> anyhow::Result<Response>;
-}
-
-impl ResponseExt for Response {
-    fn custom_error_for_status(self) -> anyhow::Result<Response> {
-        match self.error_for_status_ref() {
-            Ok(_) => Ok(self),
-            Err(err) => {
-                let body = self.text()?;
-                Err(err).context(format!("Body: {:?}", body))
-            }
-        }
-    }
-}

src/main.rs

@@ -1,6 +1,7 @@
 mod github;
 mod mailgun;
 mod team_api;
+mod utils;
 mod zulip;
 
 use crate::github::SyncGitHub;

src/team_api.rs

@@ -1,3 +1,4 @@
+use crate::utils::ResponseExt;
 use log::{debug, info, trace};
 use std::borrow::Cow;
 use std::path::PathBuf;
@@ -47,7 +48,9 @@ impl TeamApi {
                     .unwrap_or_else(|_| Cow::Borrowed(rust_team_data::v1::BASE_URL));
                 let url = format!("{base}/{url}");
                 trace!("http request: GET {}", url);
-                Ok(reqwest::blocking::get(&url)?.error_for_status()?.json()?)
+                Ok(reqwest::blocking::get(&url)?
+                    .error_for_status()?
+                    .json_annotated()?)
             }
             TeamApi::Local(ref path) => {
                 let dest = tempfile::tempdir()?;

src/utils.rs

@@ -0,0 +1,41 @@
+use anyhow::Context;
+use reqwest::blocking::Response;
+use serde::de::DeserializeOwned;
+use std::str::FromStr;
+
+pub trait ResponseExt {
+    fn custom_error_for_status(self) -> anyhow::Result<Response>;
+    fn json_annotated<T: DeserializeOwned>(self) -> anyhow::Result<T>;
+}
+
+impl ResponseExt for Response {
+    fn custom_error_for_status(self) -> anyhow::Result<Response> {
+        match self.error_for_status_ref() {
+            Ok(_) => Ok(self),
+            Err(err) => {
+                let body = self.text()?;
+                Err(err).context(format!("Body: {:?}", body))
+            }
+        }
+    }
+
+    /// Try to load the response as JSON. If it fails, include the response body
+    /// as text in the error message, so that it is easier to understand what was
+    /// the problem.
+    fn json_annotated<T: DeserializeOwned>(self) -> anyhow::Result<T> {
+        let text = self.text()?;
+
+        serde_json::from_str::<T>(&text).with_context(|| {
+            // Try to at least deserialize as generic JSON, to provide a more readable
+            // visualization of the response body.
+            let body_content = serde_json::Value::from_str(&text)
+                .and_then(|v| serde_json::to_string_pretty(&v))
+                .unwrap_or(text);
+
+            format!(
+                "Cannot deserialize type `{}` from the following response body:\n{body_content}",
+                std::any::type_name::<T>(),
+            )
+        })
+    }
+}